Many athletes and non-athletes utilize weight lifting or weight training exercises to build strength and/or bulk, to prevent injury, or to improve overall condition and appearance. Typically, weight training exercises are performed with either exercise machines or free weights, i.e., barbells and weighted plates, dumbbells, etc. For various reasons, most exercise programs incorporate both machines and free weights in a variety of different exercise routines in order to maximize the effect of working out a desired number of muscle groups.
Free weights offer a number of advantages over exercise machines. For instance, they are relatively inexpensive in comparison to exercise machines. Free weights are also more versatile because a variety of exercises can be performed with one set of weights, whereas most exercise machines are designed for only one exercise. Even though some exercise machines accommodate more than one exercise, the cost of these machines usually increases proportionately with the number of exercises. Use of dumbbells also enables both arms to be exercised independently. Finally, free weights are popular among many weight lifters because the lifting movements are not restricted to prescribed planes of motion or prescribed angles.
Nevertheless, there are also a number of inherent disadvantages associated with free weights. One such disadvantage relates to safety. Although most weight room instructors strongly advise against an individual working out by himself or herself, this cautionary measure is particularly important when the lifting of free weights is involved. This is due to commonly recognized dangers such as the possibility of dropping a weight on a body part, or becoming trapped beneath a bar, which could easily occur in exercises such as bench press, incline press or squat. Additionally, through carelessness, loading and unloading of heavy weighted plates onto the ends of a bar sometimes results in an unbalanced bar that falls downward from its rack.
Another disadvantage associated with free weights relates to the fact that the weight resistance, or opposing force, that is exercised against is always directed vertically downward by gravity. Yet, the moment arm of the weight about the pivot point varies considerably throughout the full range of motion. This principle is explained in U.S. Pat. No. 3,998,454 with respect to a commonly performed exercise referred to as the dumbbell bicep curl. In short, during this exercise the applied moment arm about the elbow varies according to the sine of the angle of the lower arm with respect to the vertically oriented upper arm. The moment arm is greatest when the angle is 90.degree., and it is lowest when the angle is 180.degree. and 0.degree..
If the resistance capabilities of the muscles of the human body matched this moment arm, the degree of difficulty experienced by the exerciser would be uniform, or balanced, throughout the entire range of motion. However, as reported in U.S. Pat. No. 3,998,454, the strength generated by the human muscles during this exercise is not in fact "balanced" throughout the range of motion, and there are some "sticking points" of increased difficulty. As a result, maximum benefits are not achieved when performing a bicep curl with a dumbbell.
A pullover machine disclosed in U.S. Pat. No. 3,998,454 utilizes an eccentric cam to vary weight resistance over the range of motion for the muscles utilized in a pullover maneuver. Over the years, for various muscle groups, a number of these cam and chain machines have been designed in an attempt to match a resistance variation through a range of motion with the natural strength curve for a particular muscle group associated with the range of motion. To the extent that these machines actually do succeed in approximating a resistance variation to an appropriate strength curve, an improvement over lifting of free weights probably has been achieved.
As a result, applicant has recognized that a machine, rather than free weights, must be employed to advance the state of the art with respect to manipulating resistance variation to match a strength curve for a particular range of motion. Nevertheless, there are a number of practical disadvantages associated with cam and chain machines. These disadvantages are outlined in applicant's copending applications, entitled "Pulldown Exercise Machine" and "Dumbbell Press Exercise Machine," filed on Apr. 26, 1990, Ser. Nos. 07/514,869 and 07/514,839. Moreover, applicant is unaware of any incline press exercise machine that effectively and safely exercises the triceps, the pectoral muscles and the deltoids.
It is therefore an object of the invention to provide an incline press exercise machine that maximizes the exercise benefit attainable during an incline press maneuver while minimizing skeletal or joint stress associated therewith.
It is another object of the invention to provide an incline press exercise machine which combines the advantageous features of both free weight exercise and exercise machines without incorporating the attendant disadvantages normally associated therewith.
It is still another object of the invention to provide an incline press exercise machine which is particularly suitable for exercising one arm at a time.